---
name: "getnetgrent"
section: "3"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "freebsd", "macos"]
url: "https://new.carta.tech/setnetgrent"
---

# getnetgrent(3)

handle network group entries

Part of [setnetgrent(3)](/setnetgrent/3.md).

## NAME

setnetgrent, endnetgrent, getnetgrent, getnetgrent\_r, innetgr - handle network group entries

## LIBRARY

Standard C library (*libc*, *-lc*)

## SYNOPSIS

```
#include <netdb.h>
```

**int setnetgrent(const char \****netgroup***);** **void endnetgrent(void);**

**int getnetgrent(char \*\*restrict** *host***,**             **char \*\*restrict** *user***, char \*\*restrict** *domain***);** **int getnetgrent\_r(**size\_t size;             **char \*\*restrict** *host***,**             **char \*\*restrict** *user***, char \*\*restrict** *domain***,**             **char** *buf***\[restrict** *size***\], size\_t** *size***);**

**int innetgr(const char \****netgroup***, const char \****host***,**             **const char \****user***, const char \****domain***);**

Feature Test Macro Requirements for glibc (see [**feature\_test\_macros**(7)](/feature_test_macros/7.md)):

**setnetgrent**(), **endnetgrent**(), **getnetgrent**(), **getnetgrent\_r**(), **innetgr**():

```
    Since glibc 2.19:
        _DEFAULT_SOURCE
    glibc 2.19 and earlier:
        _BSD_SOURCE || _SVID_SOURCE
```

## DESCRIPTION

The *netgroup* is a SunOS invention. A netgroup database is a list of string triples (*hostname*, *username*, *domainname*) or other netgroup names. Any of the elements in a triple can be empty, which means that anything matches. The functions described here allow access to the netgroup databases. The file */etc/nsswitch.conf* defines what database is searched.

The **setnetgrent**() call defines the netgroup that will be searched by subsequent **getnetgrent**() calls. The **getnetgrent**() function retrieves the next netgroup entry, and returns pointers in *host*, *user*, *domain*. A null pointer means that the corresponding entry matches any string. The pointers are valid only as long as there is no call to other netgroup-related functions. To avoid this problem you can use the GNU function **getnetgrent\_r**() that stores the strings in the supplied buffer. To free all allocated buffers use **endnetgrent**().

In most cases you want to check only if the triplet (*hostname*, *username*, *domainname*) is a member of a netgroup. The function **innetgr**() can be used for this without calling the above three functions. Again, a null pointer is a wildcard and matches any string. The function is thread-safe.

## RETURN VALUE

These functions return 1 on success and 0 for failure.

## FILES

*/etc/netgroup*\
 */etc/nsswitch.conf*

## ATTRIBUTES

For an explanation of the terms used in this section, see [**attributes**(7)](/attributes/7.md).

| | | |
| --- | --- | --- |
| **Interface** | **Attribute** | **Value** |
| **setnetgrent**(), **getnetgrent\_r**(), **innetgr**() | Thread safety | MT-Unsafe race:netgrent locale |
| **endnetgrent**() | Thread safety | MT-Unsafe race:netgrent |
| **getnetgrent**() | Thread safety | MT-Unsafe race:netgrent race:netgrentbuf locale |

In the above table, *netgrent* in *race:netgrent* signifies that if any of the functions **setnetgrent**(), **getnetgrent\_r**(), **innetgr**(), **getnetgrent**(), or **endnetgrent**() are used in parallel in different threads of a program, then data races could occur.

## VERSIONS

In the BSD implementation, **setnetgrent**() returns void.

## STANDARDS

None.

## HISTORY

**setnetgrent**(), **endnetgrent**(), **getnetgrent**(), and **innetgr**() are available on most UNIX systems. **getnetgrent\_r**() is not widely available on other systems.

## SEE ALSO

[**sethostent**(3)](/sethostent/3.md), [**setprotoent**(3)](/setprotoent/3.md), [**setservent**(3)](/setservent/3.md)